Я приложил карту к валидатору, но он не сработал с первого раза.

I tapped my card on the validator, but it did not work the first time.

Breakdown of Я приложил карту к валидатору, но он не сработал с первого раза.

• я: I
• не: not
• к: to
• но: but

Questions & Answers about Я приложил карту к валидатору, но он не сработал с первого раза.

Why is it я приложил, not я прикладывал?

Приложил is the perfective past form of приложить, so it presents the action as a completed single event: the speaker tapped/placed the card once.

If you said я прикладывал карту, that would usually sound more like:

• a repeated action,
• an attempted action,
• or a process without focus on completion.

In this sentence, the speaker is describing one finished action in a sequence:

1. I tapped the card
2. but the validator didn’t work the first time

So приложил is the natural choice.

Why is it приложил and not приложила?

In the past tense, Russian verbs agree with the speaker’s gender in the singular:

• приложил = masculine speaker
• приложила = feminine speaker
• приложило = neuter
• приложили = plural

So this sentence suggests the speaker is male, or the example is just using the masculine default form.

Why is it карту and not карта?